Multiple-effect absorption refrigeration systems



June 25, 1968 J, PAPAPANU 3,389,572

MULTIPLE-EFFECT ABSORPTION REFRIGERATION SYSTEMS Filed May 51, 1967INVENTOR. JAMES A. PAPAPANU.

BY z ATTORNEY.

United States Patent 3,389,572 MULTIPLE-EFFECT ABSORPTION REFRIGERATEONSYSTEMS James A. Papapanu, Syracuse, N.Y., assignor to CarrierCorporation, Syracuse, N.Y., a corporation of Delaware Filed May 31,1967, Ser. No. 642,370 2 Claims. (Cl. 62-101) ABSTRACT OF THE DISCLGSUREA double-effect absorption refrigeration system having a primaryabsorber, a primary evaporator, a high pressure generator, a lowpressure generator, a high pressure condensing section, and a lowpressure condenser, connected to provide refrigeration. A plurality ofauxiliary absorber stages are connected in a weak solution line betweenthe primary absorber and the high pressure generator. A plurality ofauxiliary evaporator stages are connected in an intermediate solutionline between the high pressure generator and the low pressure generator,and a plurality of auxiliary evaporator stages are connected in a strongsolution line between the low pressure generator and the primaryabsorber. Stages of the auxiliary evaporators are connected byrefrigerant vapor passages with the auxiliary absorbers so as tosimultaneously concentrate and cool absorbent solution leaving thegenerator while also simultaneously heating and diluting weak solutionpassing to the generators. A low pressure refrigerant economizer isemployed to evaporate a portion of the refrigerant condensed in the lowpressure condenser to cool the remainder thereof. High pressurerefrigerant liquid is passed directly from the high pressure condenserinto the low pressure refrigerant economizer to evaporate a portionthereof and cool the remainder. The vapor formed in the economizer ispassed to another auxiliary absorber to cool and dilute weak solution.

Background of the invention This invention relates to multiple-effectabsorption refrigeration systems wherein the heat of the high pressurerefrigerant vapor formed in the high pressure generator is reused toform additional low pressure refrigerant vapor, and to furtherconcentrate absorbent solution in the low pressure generator. Both thehigh pressure refrigerant vapor and the low pressure refrigerant vaporare condensed and passed into the primary evaporator for evaporationtherein to produce the refrigeration effect from the system.

It has been previously known to pass the condensed high pressurerefrigerant directly into the primary evaporator where it is required toflash-cool down to the temperature and pressure of the primaryevaporator. This system suffers the disadvantage that relatively warmhigh pressure refrigerant liquid passing into the primary evaporatorflashes therein and produces a large amount of vapor. This flash vapormust be absorbed in the primary absorber before any useful cooling isproduced by the system, and it therefore undesirably increases theabsorber load. Furthermore, the heat of the flashed refrigerant is lostfrom the system without doing useful work, and actually increases theamount of strong solution which must be passed to the absorber in orderto absorb it. Also, the large volume of refrigerant vapor produced byflashing in the primary evaporator may entrain droplets of liquidrefrigerant which, if carried into the primary absorber, represents asignificant loss of refrigeration capacity. The liquid droplets, whichreach the absorber, are unevaporated refrigerant, which do not produceuseful cooling and 3,389,572 Patented June 25, 1968 ice which dilute theabsorbent solution in the absorber, thereby reducing the capacity of thesystem and its efliciency and increasing the heat input required to thegenerators.

In order to partially overcome some of these disadvan rages, it has beenproposed to flash-cool the high pressure refrigerant down to the lowpressure condenser temperature, thereby reducing the amount of flashvapor formed in the primary evaporator. This arrangement has advantagesin improving the capacity of the double-effect system, but it will beappreciated that the heat rejected from the flash vapor from the lowpressure condenser represents a heat loss from the system, and it wouldbe desirable to recover this heat in a manner so that it could provideuseful cooling. Furthermore, even when the refrigerant is flash-cooleddown to the temperature of the low pressure condenser, it still containsa significant amount of heat which is lost by flash-cooling in theprimary evaporator. This heat causes excessive flashing in theevaporator and its attendant disadvantages previously described, and itrepresents heat which it would be desirable to utilize in the system, ifpossible, to improve the efiiciency thereof.

In accordance with this invention, there is provided a multiple-effectabsorption refrigeration system wherein a significant amount of heat isrecovered from the refrigerant condensed in the low pressure generator,while, at the same time, the refrigerant is cooled to a lowertemperature and pressure than that in the low pressure condenser, so asto reduce loss of capacity and efficiency due to excessive flashing inthe primary evaporator.

Summary of the invention:

This invention achieves the advantages thereof by utilizing a lowpressure refrigerant economizer having a pressure therein intermediatethe pressures in the low pressure condenser and the primary absorber.The refrigerant condensed in the condenser section of the low pressuregenerator is passed directly from the low pressure generator into thelow pressure refrigerant economizer. In addition, the refrigerantcondensed in the low pressure condenser is also passed directly into thelow pressure refrigerant economizer. A portion of the refrigerant in thelow pressure refrigerant economizer is evaporated to cool the remainingrefrigerant down to a temperature only slightly above that of theprimary evaporator. The refrigerant vapor thus formed is passed into anauxiliary absorber where it is absorbed in weak solution passing fromthe primary absorber to the high pressure generator.

By this arrangement, a large portion of the excess heat contained in therefrigerant passing to the primary evaporator is absorbed into the weaksolution where it serves to usefully preheat the solution and to reducethe quantity of heat required to boil it in the high pressure generator.At the same time, the absorption of the refrigerant vapor formed in thelow pressure refrigerant economizer dilutes the weak solution into whichit is absorbed, thereby reducing the solution concentration in the highpressure generator. The dilution of the solution has the furtheradvantages of lessening the heat required to boil a given amount ofrefrigerant from the solution and thereby reducing the temperaturerequired in the generator, which in turn lessens the corrosion rate ofmetal parts therein. Also, the capacity and cost of the cooling tower orother condenser cooling means is reduced because the heat of the flashvapor is not rejected from the system through the condenser. At the sametime, it will be appreciated that by recovering the heat of the liquidrefrigerant in the weak solution, not only is the efficiency of themachine increased, but the problems with the excessive flashing in theabsorber are significantly alleviated.

Brief description of the drawing The drawing illustrates a schematiccrosssection through a double-effect absorption refrigeration system inaccordance with a preferred embodiment of this invention.

Description of the preferred emobidmclzt Referring to the drawing, thereis shown a multipleeifect absorption refrigeration system of a typehaving two effects which may use water as a refrigerant and an aqueoussolution of hygroscopic salt, such as lithium bromide, as an absorbent.Various additives may be added to the solution, such as 2-ethyl hexanol,to enhance heat transfer, and lithium hydroxide to inhibit corrosion. Asused herein weak solution refers to a solution weak in absorbent saltand absorbing power, and strong solution refers to a solution strong inabsorbent salt and absorbing power.

The double-effect absorption system comprises a high pressure generator7, a low pressure 8 having a high pressure condenser section associatedtherewith, a low pressure condenser 9, a primary absorber 11 and aprimary evaporator 10.

Primary evaporator 10 and primary absorber 11 are preferably disposedwithin a single low pressure shell 16. An internal partition 12 forms aprimary absorber chamher and an internal partition 13 forms a primaryevaporator chamber within shell 16. A plurality of evaporator heatexchange tubes 14 are arranged within partition 13 for passage of afluid medium, such as water, to be chilled by the refrigeration system.A plurality of absorber heat exchange tubes 15 are disposed withinpartition 12 and arranged for passage of a cooling medium, such aswater, to a suitable heat rejection location, such as a conventionalcooling tower.

Liquid refrigerant is distributed over evaporator tubes 14 and isevaporated to cool the fluid passing through the evaporator tubes. Theunevaporated refrigerant liquid passes from the bottom of a sump formedby partition 13 through an evaporator recirculation pump 17 andrecirculation passage 18 from which it is again distributed overevaporator tubes 14.

Cool, concentrated, strong absorbent solution is distributed overabsorber tubes 15 and cooled by heat exchange with the medium passingtherethrough. A portion of the absorbent solution collected in thebottom of a sump formed by partition 12 is recirculated by absorberrecirculation pump 19 through recirculation line 20 from which it isagain discharged over absorber tubes 15. A single electric motor 21 mayoperate both pumps 17 and 19.

The absorbent solution in primary absorber 11 is diluted by absorptionof refrigerant vapor therein from primary evaporator 10. Cold,moderately weak absorbent solution passes through moderately weaksolution passage 25 from the bottom of partition 12 and shell 16 intothe first stage 27 of a low pressure auxiliary absorber. From there, themoderately weak solution passes into second stage 28, third stage 29,and fourth stage 30 of the low pressure auxiliary absorber. Each of thestages may be substantially similar and preferably comprises a pluralityof perforated liquid distribution pans 31 arranged for cascading flow ofliquid from one pan to the succeeding pan throughout each stage. Aconnecting passage 32 passes solution from first stage 27 to secondstage 28 and similar connecting passages are provided between thesucceeding stages. A refrigerant vapor inlet passage 33 admitsrefrigerant vapor to be absorbed into first stage 27, and similarrefrigerant vapor inlet passages 34, 35 and 36 admit refrigerant vaporinto their respective succeeding stages of the low pressure auxiliaryabsorber.

A low pressure weak solution pump 40 passes warm weak solution from thelast stage 30 of the low pressure auxiliary absorber through weaksolution passage 41 to the first stage of a high pressure auxiliaryabsorber. First stage 50 of the high pressure auxiliary absorber may besimilar in construction to first stage 27 of the low presto a secondstage 53 of the high pressure auxiliary absorber. Second stage 53 isprovided with a refrigerant vapor passage 54 for admitting refrigerantvapor into the stage for absorption into absorbent solution therein. Theresulting very weak, very warm, absorbent solution is passed throughvery weak solution line 55 by very Weak solution pump into high pressuregenerator 7 for concentration therein. Pumps 44) and 60 may be driven bya single electric motor 61.

High pressure generator 7 includes generator heat exchange tubes forpassing steam in heat exchange relation with absorbent solution therein.Other heating media may be employed, or alternatively, the generator maybe directly fired by a combustible gas. The absorbent solution ingenerator 7 is boiled to vaporize refrigerant and to concentrate thesolution. Hot intermediate strength absorbent solution passes from highpressure generator 7 through float valve 66 and intermediate solutionpassage 7 0, to the first stage 71 of a high pressure auxiliaryevaporator.

Stage 71 may comprise a hollow vessel in which the incoming solution isdischarged against one wall thereof to prevent carryover of liquiddroplets into the vapor outlet passage. Refrigerant vapor passage 54terminates in the vapor space within high pressure auxiliary evaporatorstage 71. This passage conducts refrigerant vapor evaporated in highpressure auxiliary evaporator first stage 71 to the last stage 53 of thehigh pressure auxiliary absorber.

Intermediate solution passes from the first stage 71 of the highpressure auxiliary absorber through a solution trap 74 in passage 75 tosecond stage 78 of the auxiliary high pressure evaporator, which may besimilarly constructed to that of the first stage 71. Refrigerant vaporpassage 51 conducts refrigerant vapor from second stage 78 of theauxiliary high pressure evaporator to first stage 50 of the highpressure auxiliary absorber.

Refrigerant vapor is evaporated from the intermediate absorbent solutionin the stages of the high pressure auxiliary evaporator, therebysimultaneously concentrating and cooling the hot intermediate strengthsolution to form moderately hot, concentrated intermediate solution. Theconcentrated intermediate solution passes through intermediate solutionpassage 79 and solution trap 80 into low pressure generator 8.

The various solution traps, such as traps 74 and 80, are designed tohave a vertical height, such that the level of solution in the legthereof connecting with the next lower pressure stage, balances thesolution level and the pressure difference from the previous higherpressure zone to prevent vapor from passing between the stages.

Low pressure generator 8 comprises a combined generator-condenser and isprovided with heat exchange tubes 83 which form a high pressurecondenser section therein. The hot refrigerant vapor formed in highpressure generator 7 passes through high pressure refrigerant vaporpassage 67 and heat exchange tubes 83 to boil the solution in the lowerpressure generator while condensing the vapor within heat exchange tubes83. The refrigerant vapor formed in the low pressure generator passesthrough low pressure refrigerant vapor passage 84 to low pressurecondenser 9. The strong absorbent solution formed in low pressuregenerator 8 passes through solution trap 35 and strong solution passage87 to the first stage 90 of an auxiliary low pressure evaporator. Therefrigerant condensed in high pressure condenser tubes 83 passes throughsteam trap 96 to low pressure refrigerant economizer 110.

First stage 90 and the succeeding stages of the low pressure auxiliaryevaporator may be constructed similarly to first stage 71 of the highpressure auxiliary evaporator. Refrigerant vapor passage 36 extends fromthe last stage 30 of the low pressure auxiliary absorber and terminatesin the vapor space in first stage 90 of the low pressure auxiliaryevaporator to conduct refrigerant vapor formed in first stage 90 to laststage 30. The strong absorbent solution passes from first stage 90 ofthe low pressure auxiliary evaporator through solution trap 89 intosecond stage 92 in which additional refrlgerant is evaporated from thesolution. The solution then passes 1nto succeeding stages 93 and 94where still further evaporation of refrigerant vapor takes place. Secondstage 92 of the low pressure auxiliary evaporator 1s 1n vaporcommunication with third stage 29 of the low pressure auxiliary absorberthrough refrigerant vapor passage 35 and similarly third stage 93 andfourth stage 94 are in communication with second stage 28 and firststage 27, through refrigerant vapor passages 34 and 33 respectlvely.

The concentrated strong absorbent solution passes from last stage 94through a solution trap into concentrated strong solution line 95 fromwhich it is discharged over absorber heat exchange tubes in primaryabsorber 11.

The low pressure refrigerant vapor passes from low pressure refrigerantvapor passage 84 into low pressure condenser 9 and is condensed thereinby heat exchange with a suitable cooling medium passing throughcondenser heat exchange tubes 97. The cooling medium re ects heat fromlow pressure condenser 9 to a suitable location, such as a coolingtower. Also, high pressure liquid refrlgerant passes from high pressurerefrigerant l quid passage 8 5 into low pressure refrigerant economizer110 and 1s partially evaporated therein by flashing, thereby cooling theremainder thereof upon being discharged in the low pressure condenser.The resulting vapor is recondensed in condenser 9.

Condensed refrigerant passes from low pressure condenser 9 throughrestriction 98 in low pressure refrigerant passage 99 and is dischargedover evaporator heat exchange tubes 14 in primary evaporator 10.

A low pressure refrigerant economizer 110 is disposed in low pressurerefrigerant liquid passage Low pressure refrigerant economizer 110 maybe slmilar in construction to auxiliary evaporator stage 71. Vaporformed in economizer 110 passes through vapor passage 112 and passage 33into first stage 27 of the low pressure absorber. Low pressurerefrigerant restriction 111 and restriction 98 are disposed in the inletand discharge passages associated with low pressure refrigeranteconomizer 110 to maintain a pressure zone therein, intermediate thepressure in low pressure condenser 9 and primary evaporator 10.Economizer 110 may be built into the low pressure auxiliary absorber ifdesired and may comprise an open pan or tray therein through which therefrigerant flows to the primary evaporator 10.

In operation, the pressures in serially connected low pressure auxiliaryabsorber stages 27, 28, 29 and 30 successively increase in the directionof solution flow therethrough from primary absorber 11 toward the highpressure auxiliary absorber and high pressure generator 7. The lowpressure auxiliary absorber stages from successively increasing pressurezones intermediate the pressures in primary absorber 11 and first stage50 of the high pressure auxiliary absorber.

Similarly, the pressure in second stage 53 of the high pressureauxiliary absorber is greater than the pressure in first stage 50thereof. Both serially connected stages from successively increasingpressure zones intermediate the pressure in last stage 30 of the lowpressure auxiliary absorber and the high pressure generator 7, in thedirection of solution flow therethrough from primary absorber 11 to highpressure generator 7.

Moderately weak, cold, absorbent solution from primary absorber 11 issuccessively diluted and heated in the stages of the low pressureauxiliary absorber by absorption of refrigerant vapor therein, to formwarm weak solution which passes to the high pressure auxiliary absorber.The warm weak solution is successively further diluted and furtherheated by absorption of refrigerant vapor therein, as it passes throughthe stages of the high pressure auxiliary absorber to form very warm,very weak absorbent solution which passes to high pressure generator 7.

The quantity of refrigerant which can be formed by boiling weak solutionin the high pressure generator at a given temperature is greatlyincreased because the solution passed thereto is very weak in absorbentsalt. Thus, a low generator temperature becomes feasible by use of thisinvention. In addition, very weak solution results in a much lowercorrosion rate of metal parts in the high pressure generator than wouldoccur with stronger solution at the same temperature level.

The intermediate strength absorbent solution from the high pressuregenerator is further concentrated as it passes through the high pressureauxiliary evaporators by the evaporation of refrigerant vapor therein.At the same time, not only is the concentration of the solutionincreased, but its temperature is reduced so that only moderately hotbut concentrated intermediate solution passes into the low pressuregenerator.

The absorbent solution is further cooled and concentrated by evaporationof refrigerant therefrom in the low pressure generator and themoderately cool strong solution is serially passed through the stages ofthe low pressure auxiliary evaporator. Still further, refrigerant vaporis evaporated from the strong solution in the low pressure auxiliaryevaporator stages. The solution is further cooled, .due to theevaporation of refrigerant therefrom and the cool concentrated strongsolution is passed to the primary absorber to absorb refrigerant. vaportherein.

In operation, both the refrigerant condensed in high pressure condenser83 and low pressure condenser 9 is passed directly from the condensersinto low pressure refrigerant economizer 110. Low pressure refrigeranteconomizer forms an evaporating zone of pressure intermediate thepressures in low pressure condenser 9 and primary evaporator 10.Consequently, a portion of each of the refrigerant streams passing tothe low pressure economizer is evaporated therein and the remainingrefrigerant liquid is cooled down to a temperature and pressurerelatively close to that existing in primary evaporator 10. Thevaporized refrigerant carries the heat of vaporization thereof throughrefrigerant vapor passages 112 and 33 into first stage 27 of the lowpressure auxiliary absorber. The refrigerant vapor is absorbed in theauxiliary absorber into weak solution passing from primary absorber 11to high pressure generator 7,. thereby both heating and diluting theweak absorbent solution.

The cooled refrigerant remaining in low pressure refrigerant economizer110 passes through a suitable restriction 111 and refrigerant liquidpassage 99,. from which it is discharged over heat exchange tubes 14 inthe primary evaporator. Since this refrigerant is cooled at a relativelylow temperature and pressure, the amount of flashing taking place in theprimary evaporator is greatly reduced. Since less refrigerant isrequired to flash in the primary evaporator, less refrigerant vapor andless non-useful cooling is required in the primary evaporator, and theabsorber load is decreased. Also, the problems, attendant flashing ofrefrigerant in the primary evaporator, such as refrigerant liquidcarryover into the absorber, are reduced, as is the amount of heat whichmust be rejected to the cooling fluid passing through absorber heatexchange tubes 15. In addition, the temperature level and heat input tothe generator is reduced because the diluted solution boils at a lowertemperature and is preheated by absorption of vapor, so the system ismore efficient and corrosion is reduced.

Thus by employing a multiple-effect absorption refrigeration system inaccordance with this invention, the heat contained in the refrigerantcondensate is re-used in the refrigeration system to provide usefulpreheating of weak solution and the efiiciency and capacity of thesystem are improved in comparison with prior arrangements.

It will be appreciated that various modifications may be made to thepreferred embodiment of this invention described herein and to thephysical construction of the components thereof without departing fromthe principles and advantages of this invention. For example, theabsorption refrigeration system may utilize more than two effects andconsequently the terms high pressure, low pressure, strong, weak andintermediate and other similar terms are used merely for clarity todistinguish relative relationship of the components, solutions,temperatures or pressures and not as a limitation on the number ofeffects in the cycle. Also, conventional heat exchangers may besubstituted for some or all the stages of the auxiliary evaporators andauxiliary absorbers if desired, although it is desirable to employ a lowpressure auxiliary absorber in any event for absorption of refrigerantvapor from the low pressure refrigerant economizer. Accordingly, thisinvention may be otherwise embodied in the scope of the followingclaims.

I claim:

1. An absorption refrigeration system comprising:

(A) a primary absorber;

(B) a primary evaporator;

(C) a high pressure generator;

(D) a low pressure generator having a high pressure condenser sectionassociated therewithin;

(E) a low pressure condenser;

(F) weak solution passage means for passing weak absorbent solution fromsaid primary absorber to said high pressure generator for concentrationtherein;

(G) intermediate solution passage means for passing intermediatestrength absorbent solution from said high pressure generator to saidlow pressure generator for further concentration therein;

(H) strong solution passage means for passing strong absorbent solutionfrom said low pressure generator to said primary absorber for absorptionof refrigerant vapor therein;

(I) high pressure refrigerant vapor passage means for passing highpressure refrigerant vapor formed in said high pressure generatorthrough the high pressure condenser section of said low pressuregenerator for condensing said vapor and heating solution in said lowpressure generator;

(I) low pressure refrigerant vapor passage means for passing lowpressure refrigerant vapor formed in said low pressure generator to saidlow pressure condenser for condensing said vapor;

(K) refrigerant vapor passage means for passing evaporated refrigerantfrom said primary evaporator to said primary absorber for absorptioninto absorbent solution;

wherein the improvement comprises:

(L) an auxiliary absorber, disposed in said weak solution passage,having a pressure therein intermediate the pressures in said primaryabsorber and said high pressure generator;

(M) a low pressure refrigerant economizer having a pressure thereinintermediate the pressures in said low pressure condenser and saidprimary evaporator and substantially the same as the pressure in saidauxiliary absorber;

(N) high pressure refrigerant liquid passage means for passingrefrigerant condensed in said high pressure condenser directly from saidhigh pressure condenser into said low presure refrigerant economizer,for evaporating a portion of said high pressure refrigerant liquid tocool the remainder thereof;

(0) low pressure refrigerant liquid passage means for passingrefrigerant condensed in said low pressure condenser directly from saidlow pressure condenser into said low pressure refrigerant economizer,for evaporating a portion of said low pressure refrigerant liquid tocool the remainder thereof; and

(P) refrigerant vapor passage means connecting said refrigeranteconomizer and said auxiliary absorber for passing refrigerant vaporevaporated in said refrigerant economizer to said auxiliary absorber forabsorption therein to thereby heat and dilute the weak solution in saidauxiliary absorber prior to passage thereof to said high pressuregenerator.

2. A method of producing refrigeration from an absorption refrigerationsystem having a primary absorber, a primary evaporator, a high pressuregenerator, a low pressure generator associated with a high pressureeondenser, and a low pressure condenser, operatively conneeted to form amultiple-erfect absorption refrigeration system, the steps comprising:

(A) evaporating refrigerant in the primary evaporator to providecooling, and absorbing the evaporated refrigerant in an absorbentsolution in said primary absorber, thereby forming weak absorbentsolution;

(B) heating said weak absorbent solution in the high pressure generatorto form intermediate strength absorbent solution and high pressurerefrigerant vapor;

(C) heating intermediate strength solution in said low temperaturegenerator by condensing high pressure refrigerant vapor in said highpressure condenser in heat exchange relation with intermediate strengthsolution in said low pressure generator to form strong absorbentsolution and low pressure refrigerant vapor;

(D) condensing said low pressure refrigerant vapor in said lowtemperature condenser;

(E) passing said. strong solution to said primary absorber forreabsorption of refrigerant vapor;

wherein the improvement comprises:

(F) passing high pressure liquid refrigerant condensed in said highpressure condenser directly from said high pressure condenser into a lowpressure evaporating zone having a pressure intermediate the pressuresin said low pressure condenser and said primary evaporator, andevaporating a portion of said high pressure refrigerant in said lowpressure evaporating zone to cool the remainder thereof;

(G) passing low pressure liquid refrigerant condensed in said lowpressure condenser directly from said low pressure condenser into saidlow pressure evaporating zone and evaporating a portion of said lowpressure refrigerant in said low pressure evaporating zone to cool theremainder thereof;

(H) absorbing the refrigerant vapor evaporated in said low pressureevaporating zone in weak solution passing from said primary absorber tosaid high pressure generator in an absorbing zone having a pressureintermediate the pressures in said primary absorber and said highpressure generator and having a pressure substantially equal to thepressure in said low pressure evaporating zone, thereby heating anddiluting weak solution passing from said primary absorber prior toassing into said high pressure generator; and

(I) passing the cooled liquid refrigerant from said low pressureevaporating zone to said primary evaporator for evaporation therein.

References Cited UNITED STATES PATENTS 2,283,213 5/1942 Katzow 62-484 X3,266,266 8/1966 Reid 62476 3,273,350 9/1966 Taylor 6210l 3,287,92811/1966 Reid 62476 3,316,727 5/1967 Bourne 62-l01 LLOYD L. KING, PrimaryExaminer.

